From f06c50409ae74df06b1d4a23ac393676310feb3b Mon Sep 17 00:00:00 2001
From: Richard Zink <Richard Zink>
Date: Tue, 13 Oct 2026 07:31:29 +0200
Subject: [PATCH] emergency: select routes that pass near the start city

---
 vendor/clouds3d.js | 67 +++++++++++++++++++++++++++++++++-------------
 1 file changed, 49 insertions(+), 18 deletions(-)

diff --git a/vendor/clouds3d.js b/vendor/clouds3d.js
index 7fb270c..6a42635 100644
--- a/vendor/clouds3d.js
+++ b/vendor/clouds3d.js
@@ -3549,15 +3549,35 @@ function emergencyCollectCandidates(net, netKey, startCity, minKm, maxKm, nearLi
         var lastX = net.pts[last], lastZ = net.pts[last + 1], lastD = net.pts[last + 2];
         var len = Math.max(0, lastD - firstD);
         var lenKm = len * KM_PER_TILE;
-        var dStart = Math.hypot(firstX - startCity.x, firstZ - startCity.z);
-        var dEnd = Math.hypot(lastX - startCity.x, lastZ - startCity.z);
-        var near = Math.min(dStart, dEnd);
-        if (near <= nearLimit && lenKm >= minKm && lenKm <= maxKm) {
-            out.push({
-                net: net, netKey: netKey, ci: ci, len: len, lenKm: lenKm, near: near,
-                score: Math.abs(lenKm - targetKm) + near * 18,
-                reverse: dEnd < dStart
-            });
+        if (lenKm >= minKm && lenKm <= maxKm) {
+            var near = Math.hypot(firstX - startCity.x, firstZ - startCity.z);
+            var startD = 0;
+            var dEnd = Math.hypot(lastX - startCity.x, lastZ - startCity.z);
+            if (dEnd < near) {
+                near = dEnd;
+                startD = len;
+            }
+            // A long road can pass close to the start city even when both
+            // of its endpoints are far away. Sample the chain coarsely.
+            if (near > nearLimit && n > 4) {
+                var step = Math.max(1, Math.floor(n / 16));
+                for (var q = step; q < n - step; q += step) {
+                    var off = k + q * 3;
+                    var dd = Math.hypot(net.pts[off] - startCity.x, net.pts[off + 1] - startCity.z);
+                    if (dd < near) {
+                        near = dd;
+                        startD = Math.max(0, Math.min(len, net.pts[off + 2] - firstD));
+                    }
+                }
+            }
+            if (near <= nearLimit) {
+                out.push({
+                    net: net, netKey: netKey, ci: ci, len: len, lenKm: lenKm,
+                    near: near, startD: startD,
+                    score: Math.abs(lenKm - targetKm) + near * 18,
+                    reverse: false
+                });
+            }
         }
         k += n * 3;
     }
@@ -3620,11 +3640,7 @@ function selectEmergencyRoutes() {
         if (used[usedKey]) continue;
         used[usedKey] = true;
         var route = emergencyChainAt(cand.net, cand.ci);
-        if (cand.reverse) {
-            route.reverse();
-            var maxD = route.length ? route[0].d : 0;
-            for (var rp = 0; rp < route.length; rp++) route[rp].d = maxD - route[rp].d;
-        } else if (route.length) {
+        if (route.length) {
             var base = route[0].d;
             for (var rp2 = 0; rp2 < route.length; rp2++) route[rp2].d -= base;
         }
@@ -3637,12 +3653,20 @@ function selectEmergencyRoutes() {
             });
             continue;
         }
-        emergencyRoutes.push({ pts: route, len: len, lenKm: len * KM_PER_TILE, nearKm: cand.near * KM_PER_TILE });
+        emergencyRoutes.push({
+            pts: route, len: len, lenKm: len * KM_PER_TILE,
+            nearKm: cand.near * KM_PER_TILE,
+            startD: Math.max(0, Math.min(len, cand.startD || 0))
+        });
     }
     for (var v = 0; v < emergencyRoutes.length; v++) {
+        var rr = emergencyRoutes[v];
+        var spread = rr.len * 0.18;
+        var d = (rr.startD || 0) + (Math.random() - 0.5) * spread;
+        d = Math.max(0, Math.min(rr.len, d));
         emergencyVehicles.push({
             route: v,
-            d: emergencyRoutes[v].len * (0.05 + 0.85 * Math.random()),
+            d: d,
             dir: Math.random() < 0.5 ? 1 : -1,
             seed: Math.random()
         });
@@ -3662,12 +3686,19 @@ function selectEmergencyRoutes() {
         candidateSample: top.slice(0, 5).map(function (c) {
             return {
                 netKey: c.netKey, ci: c.ci, lenKm: +c.lenKm.toFixed(1),
-                nearKm: +(c.near * KM_PER_TILE).toFixed(1), reverse: c.reverse
+                nearKm: +(c.near * KM_PER_TILE).toFixed(1),
+                startKm: +((c.startD || 0) * KM_PER_TILE).toFixed(1)
             };
         }),
         routeFailures: routeFailures.slice(0, 5),
         networks: nets.map(function (n) { return { key: n.key, chains: n.net.cnts.length }; }),
-        routes: emergencyRoutes.map(function (r) { return { km: +r.lenKm.toFixed(1), nearKm: +r.nearKm.toFixed(1) }; })
+        routes: emergencyRoutes.map(function (r) {
+            return {
+                km: +r.lenKm.toFixed(1),
+                nearKm: +r.nearKm.toFixed(1),
+                startKm: +(r.startD * KM_PER_TILE).toFixed(1)
+            };
+        })
     };
 }